sigprocmask(2)                 DG/UX R4.11MU05                sigprocmask(2)


NAME
       sigprocmask - examine and change blocked signals

SYNOPSIS
       #include <signal.h>

       int sigprocmask (how, set, oset)
       int how;
       const sigsett *set;
       sigsett       *oset;

   where:
       how       The manner in which the current set of blocked signals is
                 changed.

       set       NULL, or the signal set used to change the current set of
                 blocked signals.

       oset      NULL, or the current set of blocked signals.

DESCRIPTION
       The sigprocmask function is used to examine or change (or both) the
       calling process's signal mask.  If the value of the argument set is
       not NULL, it points to a set of signals to be used to change the
       currently blocked set.

       The value of the argument how indicates the manner in which the set
       is changed, and shall consist of one of the following values, as
       defined in the header <signal.h>.

                    Name                   Description

                 SIG_BLOCK     The resulting set shall be the
                               union of the current set and the
                               signal set pointed to by the
                               argument set.

                 SIG_UNBLOCK   The resulting set shall be the
                               intersection of the current set and
                               the complement of the signal set
                               pointed to by the argument set.

                 SIG_SETMASK   The resulting set shall be the
                               signal set pointed to by the
                               argument set.

       If the argument oset is not NULL, the previous mask is stored in the
       space pointed to by oset.  If the value of the argument set is NULL,
       the value of the argument how is not significant and the process's
       signal mask is unchanged by this function call; thus, the call can be
       used to enquire about currently blocked signals.

       If there are any pending unblocked signals after the call to the
       sigprocmask function, at least one of those signals shall be
       delivered before the sigprocmask function returns.

       It is not possible to block the SIGKILL and SIGSTOP signals; this
       shall be enforced by the system without causing an error to be
       indicated.

       If any of the SIGFPE, SIGILL, or SIGSEGV signals are generated while
       they are blocked, the result is undefined, unless the signal was
       generated by a call to the kill function or the raise function
       defined by the C Standard.

       If the sigprocmask function fails, the process's signal mask is not
       changed by this function call.

RETURN VALUE
       0      Successful completion.

       -1     An error occurred.  errno is set to indicate the error.

DIAGNOSTICS
       If any of the following conditions occur, the sigprocmask function
       shall return -1 and set errno to the corresponding value:

       EINVAL    The value of the how argument is not equal to one of the
                 defined values.

SEE ALSO
       sigaction(2), sigpending(2), sigsetops(3C), sigsuspend(2),
       <signal.h>.

COPYRIGHTS
       Portions of this text are reprinted from IEEE Std 1003.1-1988,
       Portable Operating System Interface for Computer Environment,
       copyright © 1988 by the Institute of Electrical and Electronics
       Engineers, Inc., with the permission of the IEEE Standards
       Department.  To purchase IEEE Standards, call 800/678-IEEE.

       In the event of a discrepancy between the electronic and the original
       printed version, the original version takes precedence.


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